The present invention is directed to intercalated layered materials and, optionally, exfoliates thereof, prepared by contacting, and thereby reacting, a layered material, e.g., a phyllosilicate, such as a smectite clay, with a coupling agent, such as a silane coupling agent, to replace platelet edge xe2x80x94OH groups with xe2x80x94Oxe2x80x94Sixe2x80x94R groups; intercalation of an onium ion spacing/compatibilizing agent and co-intercalation of the layered material with an oligomer or polymer, particularly a non-polar polymer, (e.g., as a polyolefin polymer, oligomer or copolymer) for ease of polymer intercalation. The polymer can be intercalated in the form of a polymer or oligomer capable of polymerization to form the polymer, (e.g., an ethylene oligomer or polymer and/or a propylene oligomer or polymer and/or copolymers thereof) or, can be unexpectedly easily intercalated as the oligomer or polymer by direct compounding, e.g., by combining the coupling agent reacted and onium ion-intercalated layered material and the oligomer and/or polymer in a mixing or extruding device preferably at or above the polymer melt temperature, to produce the co-intercalated layered material and the nanocomposite.
It is well known that phyllosilicates, such as smectite clays, e.g., sodium montmorillonite and calcium montmorillonite, can be treated with organic molecules, such as organic ammonium ions, to intercalate the organic molecules between adjacent, planar silicate layers, for intercalation of the polymer between the layers, thereby substantially increasing the interlayer (interlaminar) spacing between the adjacent silicate layers. The thus-treated, intercalated phyllosilicates, having interlayer spacings increased by at least 3 xc3x85, preferably at least 5 xc3x85, e.g., to an interlayer (interlaminar) spacing of at least about 10-25 xc3x85 and up to about 100 Angstroms, then can be exfoliated, e.g., the silicate layers are separated, e.g., mechanically, by high shear mixing. The individual silicate layers, when admixed with a matrix polymer, e.g., a polyamidexe2x80x94see U.S. Pat. Nos. 4,739,007; 4,810,734; and 5,385,776xe2x80x94have been found to substantially improve one or more properties of the polymer, such as mechanical strength and/or high temperature characteristics.
Exemplary prior art composites, also calledxe2x80x9cnanocompositesxe2x80x9d, are disclosed in published PCT disclosure of Allied Signal, Inc. WO 93/04118 and U.S. Pat. No. 5,385,776, disclosing the admixture of individual platelet particles derived from intercalated layered silicate materials, with a polymer to form a polymer matrix having one or more properties of the matrix polymer improved by the addition of the exfoliated intercalate. As disclosed in WO 93/04118, the intercalate is formed (the interlayer spacing between adjacent silicate platelets is increased) by adsorption of a silane coupling agent or an onium cation, such as a quaternary ammonium compound, having a reactive group which is reactive with the matrix polymer. Such quaternary ammonium cations are well known to convert a highly hydrophilic clay, such as sodium or calcium montmorillonite, into an organophilic clay capable of sorbing organic molecules.
Maxfield U.S. Pat. No. 5,514,734 (""734) discloses intercalation of clay with both a coupling agent (silane, titanate or zirconate) and onium ions together with in-situ polymerization of a nylon polymer precursor, such as polymerizable nylon monomers, e.g., xcex5-caprolactam, capable of in-situ polymerization to form a polymer that is reactive with the coupling agent to tether the polymer to the clay platelets. In accordance with the present invention, a coupling agent-reacted and onium compound-intercalated layered silicate material, hereinafter xe2x80x9cCAO Materialxe2x80x9d, is polymer melt processed for unexpectedly better dispersibility of the exfoliated platelets throughout a matrix polymer, particularly non-polar matrix polymers, such as polyolefins, especially polypropylene. In accordance with the present invention, the coupling agent preferably is not reactive with the matrix polymer, so that the matrix polymer is not tethered to the clay platelets. The Maxfield ""734 patent is hereby incorporated by reference for its disclosure of coupling agents useful in accordance with the present invention.
Edges of clay layered materials are replete with hydroxy groups (xe2x80x94OH) that make it extremely difficult to intercalate non-polar and low polarity oligomers and polymers. In accordance with an important feature of the present invention, it has been found that by reacting the xe2x80x94OH groups at the edges of clay platelets with a coupling agent, to form coupling agent covalent bonds at the clay edges, the clay becomes much more receptive to intercalation of such non-polar and low polarity oligomers and polymers, such as ethylene and propylene homopolymers and copolymers.
Useful coupling agents include those selected from the group consisting of silanes, titanates, aluminates, zirconates, and mixtures thereof; particularly the organosilanes, organotitanates, organoaluminates and/or organozirconates. The coupling agent(s) can be reacted with the xe2x80x94OH functionalities at the edges of the layered material platelets by contacting the layered material, before, during, or after onium ion intercalation, with the coupling agents, in the form of a gas, neat liquid, finely divided (e.g., non-colloidal) solid, or solute in a solvent. The concentration of coupling agent should be at least about 0.1%, preferably in the range of about 0.1% to about 10% by weight, more preferably in the range of about 0.5% to about 6% by weight, and most preferably about 1% to about 4% by weight, based on the dry weight of the layered material. The coupling agents have a structure as follows: 
wherein R1 is an organic radical, preferably an alkyl radical or an amine radical, bonded directly to the Si, Ti, Zr or Al atom (x) and at least one of R2, R3 and R4 is a radical containing a functionality, preferably an organic functionality, capable of a condensation reaction with a hydrogen from the xe2x80x94OH groups at the edges of the layered material, preferably selected from H, halogen, alkoxy, acyloxy and amine.
The xe2x80x94OH reaction of the coupling agent, e.g., silane, can be accomplished by either adding the silane to a dry onium-intercalated clay, i.e., organoclay, or by adding the silane to a water slurry of the organoclay, followed by removal of by-products and solvent during heat treatment. Alternatively, the silane also be added to the polymer-organoclay nanocomposite by integral blend methods. In this method, undiluted silane is added to the polymer either before or after introduction of the onium-intercalated clay or organoclay. It is preferable to add the silane before introduction of the clay because this allows for better dispersion and distribution of the silane into the polymer.
In addition to platelet edge xe2x80x94OH reaction with a coupling agent, the layered material also is intercalated with onium ions, e.g., ammonium ions, having a general structure of: 
Where R1, is a C2-C22 alkyl chain, straight chain or branched, and R2, R3 and R4, same or different, are hydrogen or an alkyl aryl or alkyl moiety, preferably a C1-C8 alkyl chain.
Where the intercalant polymer is a polyolefin, in accordance with the preferred embodiment, it is preferred to add 0.2% to 10% modified polyolefin, e.g., maleic anhydride-modified polyolefin, based on the total weight of the polymer, including intercalated polymer and matrix polymer, to increase the interaction between polyolefin and the silane-reacted, onium ion-intercalated layered material. The new silane-reacted, onium ion-intercalated (CAO Material) and polyolefin-intercalated organoclay nanocomposite has improved mechanical properties and heat stability over traditional polyolefin-organoclay nanocomposites, it is theorized due to the silane reaction enabling easier and more complete intercalation of the non-polar polymer between clay platelets for surprisingly better dispersibility of clay platelets and fewer, thinner tactoids.
The interlaminar spacing of adjacent layers (platelets) of the coupling agent-reacted layered material is expanded at least about 3 xc3x85, preferably at least about 5 xc3x85, to a basal spacing of at least about 10 xc3x85, preferably to at least about 15 xc3x85, and usually to about 18 xc3x85 by contacting the layered material with the onium ion spacing/compatibilizing agent for subsequent intercalation with an oligomer or polymer. The onium ion may be primary, secondary, tertiary or quaternary and preferably is a long chain (C6+) onium ion spacing/compatibilizing agent having at least one binding (ion-exchange) site capable of ion-exchanging or replacing Li+, Na+, K+, Ca+, Mg+2, or other inorganic cations that occur within the interlayer spaces between adjacent layers or platelets of the layered materials. The association of the layered material inorganic cations with the onium ion spacing/compatibilizing agent via ion-exchange enables the conversion of the hydrophilic interior clay platelet surfaces to hydrophobic platelet surfaces. Therefore, oligomers or polymers can be easily intercalated between adjacent platelets of the layered material, e.g., smectite clay platelets.
In accordance with the preferred embodiment of the present invention, a fully polymerized polymer, preferably a non-polar polymer such as polyethylene, polypropylene or copolymers thereof, having a weight average molecular weight between about 100 and about 5 million, preferably about 1,000 to about 500,000, is intercalated between adjacent platelets of the coupling agent-reacted and onium ion-intercalated layered material (CAO Material), preferably simultaneously with dispersing the intercalate into a matrix polymer, i.e., by direct compounding of the coupling agent-reacted and onium ion-intercalated layered material with the polymer. The pretreatment or reaction of the layered material edges with the coupling agent, and the intercalation of the onium ions (CAO Material) and intercalation of oligomers or polymers, results in a completely homogeneous dispersion of intercalated layered material and/or exfoliated platelets.
Optionally, the nanocomposite material can be sheared to exfoliate up to 100% of the tactoids or platelet clusters into individual platelets, preferably such that more than 80%; or more than 90% by weight of the layered material can be completely exfoliated into single platelet layers. Quick, easy, and completely homogeneous dispersion of the spacing/compatibilizing agent-reacted, onium ion/polymer co-intercalated layered material in a matrix polymer is achieved and the resulting nanocomposite has unexpectedly easy polymer intercalation and homogeneous dispersion of the intercalate and/or exfoliate throughout the matrix polymer.
The intercalates of the present invention can be dispersed uniformly into any matrix polymer to form a polymer/clay intercalate or polymer/clay exfoliate by direct compounding of the coupling agent-reacted and onium ion-intercalated clay with sufficient oligomer or polymer intercalant for intercalation of the clay to form a polymer intercalated clay, as a concentrate, that can later be mixed with additional matrix polymer to form a nanocomposite.
In accordance with an important feature of the present invention, if an intercalant oligomer or polymer is intercalated into the coupling agent-reacted and onium ion-intercalated clay galleries, the intercalate can be directly compounded with the pristine matrix polymer, preferably the same as the polymer intercalant, to form a nanocomposite easily, while achieving a nanocomposite material with homogeneously dispersed platelets, essentially free of tactoids.
In accordance with one embodiment of the present invention, intercalates are prepared by contacting a phyllosilicate with a monomeric onium ion spacing/compatibilizing agent compound. To achieve the full advantage of the present invention, the onium ion should include at least one long chain radical (C6+) that may be aliphatic, straight or branched chain, or aralkyl. Exemplary of such suitable C6+ onium ion molecules include primary, secondary, tertiary or quaternary ammonium ions, sulfonium ions, phosphonium ions, oxonium ions, or any ion of an element in Groups V or VI of the periodic table of elements.
In accordance with an important feature of the present invention, best results are achieved by mixing the layered material with the onium ions, e.g., C6+onium ion spacing coupling agent-reacted, in a concentration of at least about 2% by weight, preferably at least about 5% by weight onium ion compound, more preferably at least about 10% by weight onium ion compound, and most preferably about 20% to about 50% by weight, based on the weight of onium ion compound and carrier (e.g., water, with or without an organic solvent for the onium ion compound) to achieve better sorption of the onium ion spacing/compatibilizing agent compound between the platelets of the layered material. Regardless of the concentration of onium ion compound in the onium ion intercalating composition, the weight ratio of oligomer or polymer intercalant:layered material should be at least 1:20, preferably at least 1:10, more preferably at least 1:5, and most preferably about 1:4 to achieve sufficient oligomer or polymer intercalation between adjacent inner surfaces of adjacent platelets of the layered material. The onium ion spacing/compatibilizing agent compound ion-exchanged with and bonded to (or complexed with) the alumino silicate platelets via ion-exchange causes surprisingly easy intercalation of the oligomer or polymer.
In accordance with an important feature of the present invention, it has been found that a coupling agent-reacted and onium ion-intercalated layered material, e.g. a phyllosilicate, such as a smectite clay, can be easily co-intercalated with an oligomer or polymer, even low polarity and non-polar polymers, to form an onium ion/polymer co-intercalate that has excellent intercalate dispersibility in a matrix polymer, particularly a non-polar matrix polymer. The intercalate also can be added to any other matrix polymer to enhance a number of properties of the matrix polymer, improving tensile properties, dimensional stability, ductility, gas-impermeability, elongation, and the like.
The coupling agent treatment, onium ion/polymer co-intercalating process of the present invention provides an intercalate that can be added, particularly by direct compounding (mixing the intercalate directly into a matrix polymer melt) of the intercalate with any matrix polymer, e.g., all market available resin systems, particularly non-polar polymers.
Whenever used in this Specification, the terms set forth shall have the following meanings:
xe2x80x9cLayered Materialxe2x80x9d shall mean an inorganic material, such as a smectite clay mineral, that is in the form of a plurality of adjacent, bound layers and has a thickness, for each layer, of about 3 xc3x85 to about 50 xc3x85, preferably about 10 xc3x85.
xe2x80x9cPlateletsxe2x80x9d shall mean individual layers of the Layered Material.
xe2x80x9cIntercalatexe2x80x9d or xe2x80x9cIntercalatedxe2x80x9d shall mean a Layered Material that includes an onium ion spacing/compatibilizing agent disposed between adjacent platelets of the Layered Material to increase the interlayer spacing between the adjacent platelets at least 3 xc3x85, preferably at least 5 xc3x85, to an interlayer spacing, for example, of at least about 10 xc3x85, preferably at least about 15 xc3x85, e.g., 18 xc3x85; the Layered Material has been reacted at some of the xe2x80x94OH functionalities, at the platelet edges, with a coupling agent; and co-intercalated with an oligomer or polymer co-intercalant, to increase the d-spacing to at least about 20 xc3x85, preferably to 25 xc3x85 to 35 xc3x85.
xe2x80x9cCoupling Agent-Treated or xe2x80x9cCoupling Agent-Treatmentxe2x80x9d or xe2x80x9cCoupling Agent-Reactedxe2x80x9d shall mean the contact of a layered material with a coupling agent, e.g., a silane coupling agent, a titanate coupling agent, a zirconate coupling agent and/or an aluminate coupling agent to produce a condensation reaction between the coupling agent and xe2x80x94OH radicals at the edges of the platelets of the Layered Material.
xe2x80x9cIntercalationxe2x80x9d shall mean a process for forming an Intercalate.
xe2x80x9cOnium Ion Spacing/compatibilizing agentxe2x80x9d or xe2x80x9cOnium Ion Compoundxe2x80x9d shall mean an organic compound that includes a positively charged atom selected from the group consisting of a nitrogen atom, a phosphorous atom, a sulftir atom or an oxygen atom, preferably a quaternary ammonium compound, and when dissolved in water and/or an organic solvent, an anion dissociates from the onium ion spacing/compatibilizing agent leaving an onium cation that can ion-exchange with a silicate platelet exchangeable cation, e.g., Na+, Ca+2, Li+, Mg+2, or K+, thereby binding to the silicate platelet inner surface.
xe2x80x9cCo-Intercalationxe2x80x9d shall mean a process for forming an intercalate by intercalation of an onium ion spacing/compatibilizing agent and, at the same time or separately, intercalation of a polymer, or intercalation of an oligomer.
xe2x80x9cConcentratexe2x80x9d shall mean an intercalate or exfoliate, formed by the Coupling Agent Treatment and Co-Intercalation of a Layered Material to form a concentrate comprising 10-90% oligomer or polymer (same as or different than the matrix polymer) and 10-90% Intercalate.
xe2x80x9cIntercalating Carrierxe2x80x9d shall mean a carrier comprising water and/or an organic solvent used with the onium ion spacing/compatibilizing agent and/or with the intercalant oligomer or polymer to form an Intercalating Composition capable of achieving Intercalation of the onium ion spacing/compatibilizing agent and, at the same time or separately, intercalation of the oligomer or polymer between platelets of the Layered Material.
Intercalating Compositionxe2x80x9d or xe2x80x9cIntercalant Compositionxe2x80x9d shall mean a composition comprising a Layered Material together with an onium ion spacing/compatibilizing agent and/or an oligomer or polymer, with or without an Intercalating Carrier.
xe2x80x9cExfoliatexe2x80x9d or xe2x80x9cExfoliatedxe2x80x9d shall mean individual platelets of a Coupling Agent-Treated, Co-Intercalated Layered Material or tactoids or clusters of individual platelets, e.g., 2-10 platelets, preferably 2-5 platelets, that are smaller in total thickness than the non-exfoliated. Layered Material, dispersed as individual platelets or tactoids throughout a carrier material, such as water, a polymer, an alcohol or glycol, or any other organic solvent, or throughout a matrix polymer.
xe2x80x9cExfoliationxe2x80x9d shall mean a process for forming an Exfoliate from an Intercalate.
xe2x80x9cMatrix Polymerxe2x80x9d shall mean a thermoplastic or thermosetting polymer that the Intercalate or Exfoliate is dispersed within to improve the mechanical strength, thermal resistance, and/or the gas (O2) impermeability of the Matrix Polymer, preferably a non-polar polymer, such as a polyolefin homopolymer or polyolefin copolymer.
xe2x80x9cCAO Materialxe2x80x9d shall mean a Layered Material that has been Coupling Agent-Reacted at a portion of the xe2x80x94OH groups and Onium Ion-Intercalated.
In brief, the present invention is directed to intercalated layered materials prepared by coupling agent reaction and co-intercalation of an onium ion spacing/compatibilizing agent (CAO Material) and co-intercalated with an oligomer or polymer between the planar layers of a swellable layered material, such as a phyllosilicate, preferably a smectite clay. The spacing of adjacent layers of the layered materials is expanded at least about 3 xc3x85, preferably at least about 5 xc3x85, to at least about 10 xc3x85, preferably to at least about 15 xc3x85, usually to about 15-30 xc3x85, e.g., 18 xc3x85 with the onium ion spacing/compatibilizing agent. The intercalation of the oligomer or polymer then increases the d-spacing of adjacent layers to at least about 20 xc3x85, preferably about 25 xc3x85 to about 35 xc3x85, generally about 28 xc3x85.
The present invention is directed to a method of preparing intercalated layered materials, prepared by coupling agent reaction of a layered material and co-intercalation of an onium ion spacing/compatibilizing agent (preparing CAO Material) and co-intercalation of the CAO Material with an oligomer or polymer into the galleries of the layered materials to form intercalates or intercalate concentrate compositions that provide new and unexpected dispersability throughout a matrix polymer, particularly a non-polar matrix polymer.
The present invention also is directed to the intercalates and exfoliates prepared from the intercalate or intercalate concentrate compositions. The exfoliates can be prepared by adding the concentrate to a matrix oligomer or matrix polymer, or adding the oligomer or polymer intercalant(s), e.g. polypropylene, to further process the composition, such as by the addition of matrix polymer and/or extrusion and compounding the polymer with the intercalate or exfoliate thereof. The presence of the intercalated oligomer or polymer in the galleries of the layered materials makes the layered materials compatible to the preferred parent matrix oligomer or polymer combination of a polyolefin and a maleic anhydride-modified polyolefin when the intercalate is added to a melt of matrix oligomers or polymers that are the same as the oligomer(s) or polymer(s) intercalated. Therefore, for example, when mixed with more matrix oligomer or matrix polymer (preferably the same polymer as the intercalant polymer), the layered materials are unexpectedly more ready to be dispersed or exfoliated in the matrix polymer. The exfoliated individual layers and tactoids of the layered materials will perform as a polymer reinforcement and molecule (gas) barrier in a matrix polymer to improve the mechanical properties and barrier properties, e.g., gas impermeability, strength and temperature resistance of the matrix polymer. The exfoliate also can be prepared by directly adding a curing agent to the oligomer/or polymer/intercalated concentrate. The curing agent will penetrate into the gallery region of the intercalate to react with the polymerizable oligomers or polymers previously intercalated in the interlayer gallery and form uniformly dispersed platelets or a multi-layer intercalate in the resulting nanocomposite.
The coupling agent-reacted and onium ion intercalated layered material (CAO Material) is intercalated by contact with the melted polyolefin and maleic anhydride-modified polyolefin oligomer or polymer intercalants, such as by direct compounding the melt in an extruder, to intercalate the CAO Material with melted oligomer or polymer intercalants between adjacent phyllosilicate platelets and optionally separate (exfoliate) the layered material into individual platelets.
Addition of the coupling agent-reacted onium ion intercalated layered silicate (CAO Material) to a matrix oligomer or matrix polymer melt enhances one or more properties, such as strength, temperature deformation, resistance, solvent resistance, dimensional stability, ductility and/or gas impermeability. The intercalate is easily, homogeneously and uniformly dispersed throughout the matrix polymer and provides new and unexpected strength properties to non-polar matrix polymers by virtue of the unexpectedly homogeneous dispersability of the intercalate and/or exfoliates throughout a matrix polymer.